The present invention relates to specific photochromic h-fused or h-annellated benzo[f]chromene compounds and their use in plastics of all types, in particular for ophthalmic purposes. The present invention relates in particular to photochromic compounds derived from benzo[f]chromenes which in their closed form have especially long wavelength absorption maxima with good efficiency in the open colored form at the same time, so that when used in phototropic lenses, they are well compatible with the indenonaphthopyrans widely used therein.
Various classes of dyes are known which undergo reversible changes in color when exposed to light of certain wavelengths, in particular sunlight. This is due to the fact that these dye molecules change to an excited colored state by energy input in the form of light, then leave this state again when the energy input is interrupted and return to their colorless or at least almost colorless normal state. These photochromic dyes include for example the naphthopyrans which have already been described with various substituents in the prior art.
Pyrans, specifically naphthopyrans and larger ring systems derived therefrom, are photochromic compounds which even today are the subject of intense investigations. Although a patent application was filed for these compounds for the first time back in 1966 (U.S. Pat. No. 3,567,605), compounds that appeared to be suitable for use in eyeglass lenses were not developed until the 1990s.
The world market for photochromic eyeglasses made of silicate as well as plastic is dominated by the colors gray and brown. Colors such as green, blue, magenta, orange or yellow play a completely subordinate role.
In all photochromic plastic lenses currently on the market, these two colors are achieved by mixtures of at least two photochromic dyes. As explained in U.S. Pat. No. 6,306,3126 [sic] these may be divided into two groups, namely those whose longest wavelength absorption maximum is above 550 nm, i.e., those which in an excited state yield a violet blue to green transmission color and those whose longest wavelength absorption maximum is below 550 nm. Their transmission color ranges from yellow to orange to red.
The first group includes 2H-naphthopyrans derived from 1-naphthols and their higher analogs derived therefrom by fusion. These are described in U.S. Pat. No. 5,698,141, U.S. Pat. No. 5,723,072, U.S. Pat. No. 6,146,554, U.S. Pat. No. 6,225,466, U.S. Pat. No. 6,331,625 and U.S. Pat. No. 6,340,765, for example. Although photochromic compounds belonging to other classes, as described in U.S. Pat. No. 4,931,220 or EP 0 600 688, have absorption maxima above 550 nm, they are no longer in commercial use because of their short lifetime and/or short bandwidth of the long wavelength absorption. The long wavelength absorption of photochromic dyes of all gray or brown photochromic plastic lenses currently available on the market (e.g., Rodenstock Perfalit ColorMatic Extra®—since 1999, Transitions Next Generation®—since 2002, Hoya Solio® 1.55—since 2004) belong to the compounds derived from 1-naphthols described above.
Dyes belonging to the second group include mostly 3H-benzopyrans and 3H-naphthopyrans which are derived from 2-naphthols and are mostly substituted with aryl or heteroaryl in position 2, as described in U.S. Pat. No. 5,244,602, U.S. Pat. No. 5,427,774, U.S. Pat. No. 5,552,090, U.S. Pat. No. 5,552,091, U.S. Pat. No. 5,585,042 and WO 97/20239. The spiroadamantane-substituted compounds described in U.S. Pat. No. 4,826,977 also belong to this group. It is possible to use 2H-naphtho[1,2—b]pyrans derived from 1-naphthols only if the open form is sterically hindered by substitution in position 5 of the system, as described in EP 1 248 778. Without this hindrance, the brightening effect is too slow for use in eyeglass lenses.
Commercially available photochromic compounds such as Reversacol Sunflower, Corn Yellow, Flame and Ruby (James Robinson) or CNN-4 and CNN-8 (Tokuyama Soda) are described in EP 0 691 965 and U.S. Pat. No. 6,719,926. These compounds all have an amino group, usually piperidine or morpholine in position 6 of the naphthopyran system, yielding a very high molar extinction (IOD>1.5) in the absorption maximum. Without this functional group, the value is approximately 1.5 lower. Unfortunately, this strongly polar substitution pattern results in strong solvatochromism, so that a portion of the dye used is in the open form in the solid solution (plastic matrix). This is manifested even in the complete absence of exciting light in lightly colored lenses. In addition the transmission after Vλis also reduced by 4 to 10%. Examples that can be mentioned here include mainly the brown variants of Rodenstock ColorMatic Extras and Hoya Solio® 1.55.
Another disadvantage is the absorption of the closed form, which has a hipsochromic shift of 20 nm to 25 nm in comparison with the dyes of the first group. The composition is coordinated, i.e., the respective concentrations of the photochromic dyes used are coordinated to achieve a gray or brown color in such a way that the desired color is achieved in normal direct or indirect sunlight. If the very short wavelength portion of the visible sunlight (380-400 nm) is selectively filtered out or blocked, e.g., by window glass with a thermal insulation coating or laminated safety glass in motor vehicles, then the lenses assume a blue color in the case of a gray lens or a gray color in the case of a brown lens. This can be observed well in brightly lit rooms with the plastic photochromic lenses available on the market today and is a cosmetic disadvantage.
Compounds that have a longer wavelength absorption of the closed form due to their structure are described in WO 02/22594. However, the important aspect here is that powerful dyes which absorb in the long wavelength range, i.e., in the violet to blue range are provided, i.e., they have the longer wavelength absorption of the open form. This has been achieved by introducing amino substituents into the naphthopyran system. These compounds have the longest wavelength absorption maxima of the open form which are not below 540 nm. Here again, however, the precoloration when used in plastic eyeglass lens materials is a disadvantage.
U.S. Pat. No. 5,869,658 describes compounds having a similar basic structure, whose open form absorbs in the desired spectral range. However, this publication discusses only indeno-fused naphtho[2,1-b]pyrans, which are also substituted by an alkoxy group in position 6. This is obligatory due to the synthesis because the ring closure does not take place without an activating substituent that makes the linkage point in p-position nucleophilic. Fused ring systems larger than the five-membered ring are neither described nor possible by this route. Furthermore, the brightening rates are very high. For light exposure in equilibrium, this leads to only a small amount of open, i.e., colored, molecules. The darkening effect is minor (ΔOD<0.5). Likewise, the absorption of the closed form, usually with maxima below 370 nm, is at a much shorter wavelength than that of the compounds of the first group. However, this is not enough to utilize the long wavelength UV portion of sunlight. The dye molecules disclosed in U.S. Pat. No. 5,869,658 are relatively planar because the repulsion of the H atoms (in positions 8 and 9 of the formula in column 21) is not very great. Example 3 is unusual because in this case the slow brightening and thus greater darkening ΔOD are achieved due to a fluorine substituent in position 2 on phenyl rings B and/or B′. This effect, which makes the ΔOD value approximately four times greater, was already described in U.S. Pat. No. 5,066,818. However, this substitution which hinders the free rotation leads to an undesirably strong dependence of the brightening on the matrix surrounding the molecule, i.e., a very broad distribution of the brightening rate when the molecular ensemble in a matrix is considered and/or an extremely different brightening rate in different plastic materials.
EP 1,230,234 also describes 2H-diarylnaphthopyrans substituted with condensed rings. Condensation within the indene ring in the structure shown here leads to compounds which usually brighten as quickly as the comparative compound C5 owing to the absence of steric hindrance between the CH2 group of the five-membered ring and the H atom in position 8. As described in U.S. Pat. No. 3,567,605, compounds having this structure have adequate photochromicity only at extremely low temperatures. With the six-membered ring, the hindrance is also very minor, the brightening is quick and thus the observed coloration is only minor. In addition, the choice of possible compounds is very small and the synthesis described allows only compounds substituted in positions 6 and 7 with activating groups. When using only one methoxy group or using less activating higher alkoxy groups, no ring closure reaction takes place. Larger alkane rings are possible through synthesis but the steric hindrance is always low in comparison with that of compounds of the structure according to U.S. Pat. No. 5,869,658 or WO 02/22594; likewise the darkening results are minor. The essential aspect of these compounds according to EP 1,230,234, however, was primarily providing intrinsically gray or brown compounds. In the open form, the (substituted) phenyl group is in meta-position to the ethylene bridge instead of being in para-position, which leads to completely different behavior which is even controversial in some cases.